In an interview on the ABC current affairs program 7.30 last night, Sales pushed Mr Turnbull to define what Australian values were, after he stumbled through an answer on the subject earlier in the day.

"We don't define ourselves, like many other countries do, by race or religion or ethnicity," he said.

"We're defined by a commitment to a common set of political values and they are … freedom, equality of men and women, mutual respect, the rule of law, democracy, a fair go. That's our Australian values.

"They are shared by other democracies, but they are in and of themselves unique."

Sales suggested that Mr Turnbull had only begun talking about a citizenship test to shore up his support in the Liberal Party, a charge the Prime Minister denied.

"I'm disappointed that you're so cynical but I'm used to it," Mr Turnbull said.

"I can run you through the opinion polls if you like, given you set them as a benchmark yourself," Sales shot back.

"What this is about, is the vast majority of Australians are pleased to see that we are standing up for Australian values," Mr Turnbull replied.

Sales also questioned the need for migrants to know English before becoming Australian citizens.

"One of Australia's most successful business leaders and greatest philanthropists is the founder of Westfield, Frank Lowy. When he came here as a refugee, he understood only a little English … Today, with that level of skill he would be unlikely to qualify for citizenship. Is that the sort of Australian we're happy to miss out on?" Sales asked.

Mr Turnbull said he was not a fair example.

"The starting point for applying to be an Australian citizen is being a permanent resident, so they're not prejudiced; but to take on that additional honour, that additional privilege of being an Australian citizen, it is perfectly fair and it is in their interest to have a competent level of English."

Sales also pushed the PM on the new test that would require applicants to prove that they had integrated into Australian society, arguing that even Christianity, which Deputy Prime Minister Barnaby Joyce said our values were based on, did not explicitly advocate equality for women.

"Part of our extraordinary nation, part of our values, is respect for women and children and the respect for the equal rights of women," Mr Turnbull said.

"I'm surprised you're challenging this on the ABC.

"I don't think your heart's in it actually, Leigh."

Sales didn't respond to the quip.

When Sales asked Mr Turnbull whether Mr Morrison would retain the Treasury portfolio in a Cabinet reshuffle, the Prime Minister was indignant.

"Of course he will. Look, Scott is doing an outstanding job and it is such a disappointment, I have to say, that you're focused on the politics," Mr Turnbull said.

With a smirk, Sales interrupted to remark: "You're in the business of politics I'm afraid, Prime Minister."

"No, I know I'm in the business of politics but, can I say to you, your viewers, they're interested in energy, they want to know about how we're reducing the cost of energy," the PM answered.

Later in the interview, Mr Turnbull denied there was "open warfare" between him and former prime Minister Tony Abbott.

"Totally unfair. Ridiculous thing to say," he said.

"My job as Prime Minister is to deliver on my commitments to the Australian people. I'm not interested in personalities or politics of that kind."